Enrichment device



July 4., 1961 Filed May 9, 1957 J. DOLZA ET AL ENRICHMENT DEVICE 2 Sheets-Sheet l INVENTORS.

ATTORNEY- y 1961 J. DOLZA ET AL 2,990,826

ENRICHMENT DEVICE Filed May 9, 1957 2 Sheets-Sheet 2 United States Patent 9 2,990,826 ENRICHMENT DEVICE John Dolza, Fenton, and William H. Kolbe, Huntington Woods, Mich, assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed May 9, 1957, Ser. No. 658,186 7 Claims. (Cl. 123-139) The present invention relates to an enrichment device for a fuel injection system. More particularly, this device relates to an improved fuel metering valve construction for use with a fuel injection system of the type shown in copending application Serial No. 658,091, Dolza et al.

' filed May 9, 1957, and now Patent No. 2,914,051, granted Nov. 24, 1959.

In this device a simplified metering valve has been developed which provides supplementary quantities of fuel to the metering valve under conditions when the output of the main supply pump is low as occurs when the engine is being started or operating at very low speeds particularly with the engine cold.

In previous mechanisms of the type utilized in the noted application, starting fuel enrichment has been achieved by positioning the metering valve in a maximum fuel output position for a fixed time interval. This type of enrichment control has been found wanting for at least two reasons. In the first instance, such devices have not been truly responsive to engine temperature and therefore frequently overly enrich the mixture under conditions not requiring supplemental fuel. This is particularly likely to occur when starting a partially warm engine. Secondly, such devices have relied solely upon the main pump to provide the requisite amounts of fuel for starting enrichment or while passing through severe transients at low engine speed. Relying solely upon a displacement pump has been unsatisfactory due to the necessity of providing a pump with a high output at low speeds which consequently requires bypassing a considerable quantity of fuel under normal operating conditions. On the other hand, relying on a pump having a lesser low speed capacity results in insufiicient fuel under the conditions suggested.

The present enrichment device avoids these problems and permits the use of a main fuel pump having a relatively low starting or cranking capacity which, since close clearances do not have to be maintained, it will be apparent, is considerably cheaper to use than a high capacity pump. It is therefore an object of the present invention to provide an improved metering valve construction which utilizes a low capacity make-up fuel pump to supply fuel to the metering valve under conditions where the output of the main fuel pump is insufii- 'cient to meet the cold starting or low speed operating needs of the fuel system.

The details of the present invention as well as other objects and advantages are set forth in the description r which follows.

In the drawings: FIGURE 1 shows a fuel injection the present invention; and

FIGURE 2 is an enlarged view of the metering valve. Except as will otherwise be hereinafter particularly system embodying pointed out, the present fuel injection system functions in the same manner as that shown in the aforenoted co pending application.

A fuel induction casing is shown at and includes an intake air passage 12 having a tapered plug 14 formed therein and defining an annular venturi 16 with the casing member. A throttle valve 18 is mounted in the intake passage 12 posteriorly of the venturi 16. A signal ice trolled by a control mechanism of the type described in the aforenoted copending application.

'A fuel metering mechanism is shown generally at 22 and includes a fuel metering valve 24, a diaphragm 26 for controlling the valve, a source of fuel under pressure 28 for delivering fuel to the metering valve and a supply conduit 30. Conduit 30 in turn supplies a distributor 29 from which feeder lines 31 are adapted to deliver metered quantities of fuel to the individual cylinder nozzles 32. Each nozzle 32 is adapted to supply fuel to an individual induction passage 33 just anterior of the associated cylinder 35. It is to be understood that each of the feeder lines 31 supplies an individual nozzle 32 disposed in a separate cylinder induction passage 33.

The fuel metering mechanism 22 includes a casing 'member 34 having a bore 36 formed therethrough and within which bore a sleeve 38 is suitably fixed. A spindle member 40 includes a land portion 42 pressed within the lower end of the sleeve 38 and is cored to provide a fuel passage 44 which delivers fuel to a plurality of radial ports 46. The fuel, under pressure proportional to engine speed, is supplied from an engine driven pump 48 in reservoir 50 to supply conduit 52 and is delivered through a port 54 in casing 34. Fuel flows to a chamber 56 in casing 34 where it passes through a filter element 58 up through passage 44 in spindle 40 and out of the radial ports 46 to the interior of the fixed sleeve 38.

Sleeve 38 includes a first set of radial passages 60 which communicate the interior of sleeve 38 with an annular chamber 62 formed within bore 36 of the casing 34. Fuel outlet passages 64 are formed in casing 34 and either communicate with a fuel manifold or, as shown in the drawing, with the individual cylinder supply conduits 30. An additional set of radial ports 66 are formed in sleeve 38 in axially spaced relation from ports 60. Radial ports 66 communicate the interior bore of sleeve 38 with a counterbored portion 68 of bore 36. Any fuel which flows through radial passages 66 is returned to the supply reservoir 50 through a port 70 in casing 34 and a conduit 72.

An additional radial passage 74 is formed in sleeve 38 and is fed through casing passage 76 with fuel from a conduit 78 leading from a low capacity make-up pump 80. Pump 80 is also provided for the purpose of supplying low pressure make-up fuel to the reservoir 50 from a sump or gasoline tank 81. Passage 74 in sleeve 3-8 communicates with a longitudinal passage 82 which also communicates with an annular passage 84 formed in the upper end of the sleeve.

A hollow cylindrical valve member is slidably disposed in the upper end of sleeve 38 and is of such a length as to extend axially past the radial passage 66 when in its lowermost position. The slidable valve member 90 is closed at its upper end and opened at its lower end and is adapted to internally seat upon a stud portion 92 extending upwardly from the spindle member 40 to limit the downward movement of said valve member.

A linkage mechanism is indicated generally at 94 and is adapted to control the axial position of valve 90in accordance with the position of diaphragm 26. As described in the aforementioned copending application, the position of the diaphragm 26 is normally determined by the quantity of air flow through the venturi 16 as manifested by a vacuum force in an annular chamber 102 formed in the casing member 10 and transmitted to the diaphragm through a conduit 104. The metering control vacuum force in chamber 102 is reinforced or supplemented by an additional vacuum force created in the induction passage when the signal modifier valve 20 .is closed as described in Patent No. 2,914,051. Conduit 106 communicates the bottom side of diaphragm 26 with the induction passage 12 anteriorly of modifier valve 20.

The axial position of the slidable'valve member 90 is determined by the differential effect of fuel pressure with- .in sleeve 38 which acts on the metering valve tending to move the latter upwardly and the vacuum force acting on diaphragm 26 tending to move the latter downwardly.

A set of radial passages 110 are formed in the movable valve member 90 and are adapted to register with annular passage84. Under normal operating conditions, however, valve member 90 is maintained in the upper regions of sleeve 38 whereby the radial passages 110 are out of registry with the annular sleeve passage 84. Further, the lower end 112 of the valve member coacts with the radial passages 66 to determine the quantity of fuel which is bypassed to the counterbore 68 and hence back to the reservoir 50. As air flow through the venturi 16 increases the lower end 112 of the valve member 90 increasingly reduces the quantity of fuel bypassed and hence increases the quantity of fuel delivered to the individual cylinder conduits 30.

When the output of the main fuel supply pump 48 is very low, as would be the case when the engine was being cranked preliminary to starting or under very low engine speed operation particularly when the engine is cold, the fuel pressure within sleeve 38 is very low. In this case, the cranking vacuum acting on the diaphragm 26 is adapted to move the slidable valve member 90 downwardly to seat on stud 92', fully closing radial ports 66 and moving the radial passages 110 into registry with the annular passage 84. Fuel from the make-up pump 80 is then supplied to the interior of the sleeve 38 and thereby delivered to the outlet passage 64 and cylinder supply conduits 30.

The force exerted upon the top of the plunger 90, by the signal modifier imposed vacuum on the control diaphragm 26, varies with ambient temperature. Thus, the plunger is not necessarily pushed down to seat on stud 92 but may modulate flow through the bypass hole opening. This permits the correct amount of fuel to enter the engine for starting at all temperatures.

In this way a supplemental quantity of fuel is supplied from the make-up pump 80 under conditions when the main pump 48 is being driven at speeds inadequate to supply the fuel required for suitable enrichment of the fuel-air mixture.

In order to preclude fuel flowing out of conduit 78 when the main fuel pump pressure is sufficient to supply the required fuel, a check valve 114 is provided in the conduit which will block the reverse flow of fuel therethrough.

We claim:

1. A fuel injection system for an internal combustion engine comprising an air intake passage, a plurality of induction passages communicating with the intake passage for delivering air to the individual cylinders of said engine, a venturi formed in said intake passage, a throttle valve disposed in said intake passage posteriorly of said venturi, a source of fuel under pressure, conduit means for communicating said fuel source with the induction passages, valve means disposed intermediate said fuel source and said conduit means for controlling flow of fuel through said valve in accordance with the mass of air flowing through said venturi, means for supplying an additional quantity of fuel to said valve means, said valve means including a part thereof normally blocking the delivery of said additional fuel to said cylinders, and means for moving said valve means part to a position permitting said additional fuel supplying means to deliver fuel to said induction passages during low speed operation of said engine.

2. A fuel injection system for an internal combustion engine comprising an air intake passage, a plurality of induction passages communicating with the intake passage for delivering air to the cylinders of said engine,

a venturi formed in said intake passage, a throttle valve disposed in said intake passage posteriorly of said venturi, a source of fuel under pressure, conduit means for communicating said fuel source with the induction passages, valve means disposed intermediate said fuel source and said conduit means for controlling flow of fuel through said valve in accordance with the mass of air flowing through said venturi, a pump for supplying an additional quantity of fuelto said valve means, said valve means including a part thereof normally blocking the delivery of said additional fuel to said cylinders, and means for moving said valve means part to a position permitting said pump to deliver fuel to said induction passages during low speed operation of said engine.

3. A fuel injection system for an internal combustion engine comprising an air intake passage, a plurality of induction passages communicating with the intake passage for delivering air to the cylinders of said engine, a venturi formed in said intake passage, a throttle valve disposed in said intake passage posteriorly of said venturi, a first pump for supplying fuel under pressure, conduit means for communicating said pump with the induction passages, valve means disposed intermediate said pump and said conduit means for controlling flow of fuel through said valve in accordance with the mass of air flowing through said venturi, a second pump for supplying an additional quantity of fuel to said valve means, said valve means including a part thereof for controlling the delivery of said additional fuel to the valve means, and means for moving said valve means to a position permitting said first and second pumps to deliver fuel to said valve means during the low speed operation of said engine.

4. A fuel injection system for an internal combustion engine comprising an air intake passage, venturi means formed in said intake passage, a throttle valve in said induction passage posteriorly of said venturi, a plurality of induction passages communicating the intake passage with the individual cylinders of the engine, an annular chamber formed in said induction passage and communicating with said venturi, a main supply pump for providing fuel under pressure, conduit means for delivering said fuel under pressure to the induction passages, a metering valve for controlling the quantity of fuel flowing through said conduit means, a diaphragm device for controlling the actuation of said metering valve, conduit means communicating the annular chamber in said induction passage with said diaphragm whereby the diaphragm is adapted to increase the fuel flow through the metering valve as a mass of air flowing through the venturi increases, said metering valve including a slidable sleeve member adapted to be moved by the differential effect of fuel pressure and said diaphragm device, a fuel bypass controlled by said slidable valve member, said valve member being adapted under normal operating conditions to permit a continuous bypass of fuel to control the quantity of fuel delivered to said conduit means, a second pump of lower capacity than said first pump for supplying fuel to the first pump and adapted to supply fuel to the metering valve, said metering valve being shiftable to a position permitting said second pump to deliver fuel to said 0on duit means when the main fuel pump output pressure drops below a given value.

5. A fuel injection system for an internal combustion engine comprising an air intake passage, a plurality of induction passages for communicating with the intake passage for delivering air to the cylinders of said engine, a venturi in said intake passage, a throttle valve disposed in said intake passage posteriorly of said venturi, a source of fuel under pressure proportional to engine speed, conduit means for communicating said fuel source with said induction passage proximate said cylinders, valve means associated with said conduit means, means responsive to the mass of air flowing through said venturi-for controlling said valve means, a source of low pressure fuel,

and conduit means for delivering said low pressure fuel to said valve means, said valve means including a cylindrical sleeve portion having a set of radial ports adapted to register 'with the low pressure fuel conduit means whereby said low pressure fuel is supplied to said cylinders, said engine speed responsive fuel pressure normally biasing said valve means to a-position blocking the flow of low pressure fuel to said induction passages.

6. A fuel injection system for an internal combustion engine comprising an air intake passage, a plurality of induction passages communicating with the intake passage for delivering air to the cylinders of said engine, a venturi in said intake passage, a throttle valve disposed in said intake passage posteriorly of said venturi, a source of fuel under pressure proportional to engine speed, conduit means communicating said fuel source with said induction passage proximate said cylinders, valve means associated with said conduit means, means responsive to the mass of air flowing through said venturi for controlling said valve means, a source of low pressure fuel, conduit means for delivering said low pressure fuel to said valve means, and a check valve in said'latter conduit means to prevent reverse flow therethrough, said valve means including a cylindrical sleeve portion having a set of radial ports adapted to register with the low pressure fuel conduit means whereby said low pressure fuel is supplied said intake passage posteriorly of said venturi, a source of fuel under pressure proportional to engine speed, conduit means for communicating said fuel source with said induction passages proximate said cylinders, valve means associated with said conduit means, means responsive to the mass of air flowing through said venturi for controlling said valve means, said valve means including a valve casing, a spindle element fixed Within said casing and extending longitudinally thereof in radially spaced relation to the casing, a longitudinal passage extending through part of length of said spindle, radial port means communicating the longitudinal passage with the space between said spindle and easing, a fuel outlet passage formed in said casing and communicating with said space, said fuel under pressure being continuously supplied to the longitudinal passage, a cylindrical sleeve member open at one end and slidably mounted in said casing, a fuel bypass port in said casing, the open end of said slidable sleeve member coacting with the bypass port to control the quantity of fuel bypassed, conduit means for returning bypass fuel to the fuel source, radial port means formed in the sleeve member, a source of low pressure fuel, and conduit means for delivering said low pressure fuel to said casing, the closed end of said sleeve being adapted to seat upon said spindle when said engine speed responsive pressure drops below a given value, said radial sleeve ports registering with the low pressure fuel conduit means when said sleeve is seated whereby low pressure fuel is supplied to said induction passages.

References Cited in the file of this patent UNITED STATES PATENTS 2,785,669 Armstrong Mar. 19, 1957 

